The technical field of this invention is surgical instruments and, in particular, inflation catheters and detachable balloon systems for implanting structures in vivo.
Balloon catheters are used in a variety of medical procedures. Balloon catheters have been used extensively in the cardiovascular area, for example, to occlude vessels in certain types of surgery and to expand blood vessels as in an angioplasty procedure. Inflation catheters carrying detachable balloons have been used to treat urinary incontinence as disclosed in, e.g., U.S. Pat. No. 4,832,680, issued May 23, 1989; U.S. Pat. No. 4,802,479, issued Feb. 7, 1989; and U.S. Pat. No. 4,773,393, issued Feb. 27, 1988. These patents describe an extensible, inflatable containment membrane which is implanted between the urethra and the subcutaneous corpus spongiousum of a patient to overcome urinary incontinence.
Inflation catheters carrying detachable balloons have also been used in endoscopic or cystoscopic methods to treat vesicouretal reflux. In such a procedure, described in U.S. Pat. No. 5,304,123, a needle is directed through a cystoscope and inserted into the subureteral region of a refluxing bladder to establish a pocket. A catheter or similar delivery device can be inserted into this pocket in the subureteral region carrying a balloon. The balloon can then be inflated and sealed. In one embodiment, the balloon is delivered on an inflation catheter through the cystoscopic needle. The uninflated balloons must be sized to fit on the tip of the catheter and for delivery within the cystoscopic needle. Once delivered to the desired area within a patient's body, the balloon is inflated or filled with a biocompatible material supplied through the catheter. The catheter is then withdrawn leaving the balloon in place. Preferably, the balloon includes a sealing mechanism so that the balloon seals itself upon inflation and removal of the catheter.
Additional endoscopic procedures involving inflation catheters with detachable balloons are disclosed in U.S. Pat. No. 5,411,475, issued May 2, 1995. According to this patent, a scope is provided for directly visualizing a target site in vivo. The scope includes a viewing means, a sheath, and a positioning element extending through the sheath. An uninflated, detachable balloon attached to a catheter is passed through the lumen of the positioning device, such as a hollow needle, to the target site. The balloon is then inflated and detached at the target site. The disclosed system and method can be used in a variety of medical procedures including birth control procedures.
Balloons useful in these procedures must be very small. In some procedures, a 19 gauge needle small enough to fit within standard cystoscopic equipment is used as a cystoscopic positioning device. In one system, a thin walled cystoscopic needle has a 19 gauge outer diameter and has an inner diameter of a standard 18 gauge needle (i.e., 0.036 inches). Accordingly, a balloon useful for such procedures must be readily passable though the inner lumen of this needle. The balloon is also preferably self-sealing upon inflation and detachment from the catheter. The balloon should also be detachable from the catheter with a detachment force that is appropriate to the application. The detachment force must be high enough to allow the balloon to inflate without premature detachment, and low enough to allow the catheter to be readily withdrawn without dislodging the inflated balloon from the target site.
One example of a balloon known in the art is provided in U.S. Pat. No. 4,819,637, issued Apr. 11, 1989. This balloon includes a valve base having a smooth surface cylindrical bore extending therethrough for attachment to a catheter and a "duck-bill" type valve attached to the valve base. An additional detachable balloon is described in U.S. Pat. No. 4,832,680. That balloon is apparently larger than balloons delivered through a cystoscopic needle (it is delivered through a trocar) and includes a solid valve core that is prestressed by a surrounding compression band and a needle stop. The core and compression band are also surrounded by titanium tubing that forms a needle stop to prevent damage to the balloon. The balloon membrane is bonded to the compression band.
Known balloons perform poorly when miniaturized for delivery through small lumens, such as a cystoscopic needle, or they are expensive to make in miniature or both. Accordingly, it is an object of the present invention to provide a low cost, easy to manufacture, highly efficient miniature balloon for detachable delivery in vivo.